net/dccp/minisocks.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  net/dccp/minisocks.c
   4  *
   5  *  An implementation of the DCCP protocol
   6  *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   7  */
   8
   9 #include <linux/dccp.h>
  10 #include <linux/gfp.h>
  11 #include <linux/kernel.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/timer.h>
  14
  15 #include <net/sock.h>
  16 #include <net/xfrm.h>
  17 #include <net/inet_timewait_sock.h>
  18
  19 #include "ackvec.h"
  20 #include "ccid.h"
  21 #include "dccp.h"
  22 #include "feat.h"
  23
  24 struct inet_timewait_death_row dccp_death_row = {
  25         .sysctl_max_tw_buckets = NR_FILE * 2,
  26         .hashinfo       = &dccp_hashinfo,
  27 };
  28
  29 EXPORT_SYMBOL_GPL(dccp_death_row);
  30
  31 void dccp_time_wait(struct sock *sk, int state, int timeo)
  32 {
  33         struct inet_timewait_sock *tw;
  34
  35         tw = inet_twsk_alloc(sk, &dccp_death_row, state);
  36
  37         if (tw != NULL) {
  38                 const struct inet_connection_sock *icsk = inet_csk(sk);
  39                 const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1);
  40 #if IS_ENABLED(CONFIG_IPV6)
  41                 if (tw->tw_family == PF_INET6) {
  42                         tw->tw_v6_daddr = sk->sk_v6_daddr;
  43                         tw->tw_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
  44                         tw->tw_ipv6only = sk->sk_ipv6only;
  45                 }
  46 #endif
  47
  48                 /* Get the TIME_WAIT timeout firing. */
  49                 if (timeo < rto)
  50                         timeo = rto;
  51
  52                 if (state == DCCP_TIME_WAIT)
  53                         timeo = DCCP_TIMEWAIT_LEN;
  54
  55                 /* tw_timer is pinned, so we need to make sure BH are disabled
  56                  * in following section, otherwise timer handler could run before
  57                  * we complete the initialization.
  58                  */
  59                 local_bh_disable();
  60                 inet_twsk_schedule(tw, timeo);
  61                 /* Linkage updates.
  62                  * Note that access to tw after this point is illegal.
  63                  */
  64                 inet_twsk_hashdance(tw, sk, &dccp_hashinfo);
  65                 local_bh_enable();
  66         } else {
  67                 /* Sorry, if we're out of memory, just CLOSE this
  68                  * socket up.  We've got bigger problems than
  69                  * non-graceful socket closings.
  70                  */
  71                 DCCP_WARN("time wait bucket table overflow\n");
  72         }
  73
  74         dccp_done(sk);
  75 }
  76
  77 struct sock *dccp_create_openreq_child(const struct sock *sk,
  78                                        const struct request_sock *req,
  79                                        const struct sk_buff *skb)
  80 {
  81         /*
  82          * Step 3: Process LISTEN state
  83          *
  84          *   (* Generate a new socket and switch to that socket *)
  85          *   Set S := new socket for this port pair
  86          */
  87         struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC);
  88
  89         if (newsk != NULL) {
  90                 struct dccp_request_sock *dreq = dccp_rsk(req);
  91                 struct inet_connection_sock *newicsk = inet_csk(newsk);
  92                 struct dccp_sock *newdp = dccp_sk(newsk);
  93
  94                 newdp->dccps_role           = DCCP_ROLE_SERVER;
  95                 newdp->dccps_hc_rx_ackvec   = NULL;
  96                 newdp->dccps_service_list   = NULL;
  97                 newdp->dccps_service        = dreq->dreq_service;
  98                 newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo;
  99                 newdp->dccps_timestamp_time = dreq->dreq_timestamp_time;
 100                 newicsk->icsk_rto           = DCCP_TIMEOUT_INIT;
 101
 102                 INIT_LIST_HEAD(&newdp->dccps_featneg);
 103                 /*
 104                  * Step 3: Process LISTEN state
 105                  *
 106                  *    Choose S.ISS (initial seqno) or set from Init Cookies
 107                  *    Initialize S.GAR := S.ISS
 108                  *    Set S.ISR, S.GSR from packet (or Init Cookies)
 109                  *
 110                  *    Setting AWL/AWH and SWL/SWH happens as part of the feature
 111                  *    activation below, as these windows all depend on the local
 112                  *    and remote Sequence Window feature values (7.5.2).
 113                  */
 114                 newdp->dccps_iss = dreq->dreq_iss;
 115                 newdp->dccps_gss = dreq->dreq_gss;
 116                 newdp->dccps_gar = newdp->dccps_iss;
 117                 newdp->dccps_isr = dreq->dreq_isr;
 118                 newdp->dccps_gsr = dreq->dreq_gsr;
 119
 120                 /*
 121                  * Activate features: initialise CCIDs, sequence windows etc.
 122                  */
 123                 if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) {
 124                         sk_free_unlock_clone(newsk);
 125                         return NULL;
 126                 }
 127                 dccp_init_xmit_timers(newsk);
 128
 129                 __DCCP_INC_STATS(DCCP_MIB_PASSIVEOPENS);
 130         }
 131         return newsk;
 132 }
 133
 134 EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
 135
 136 /*
 137  * Process an incoming packet for RESPOND sockets represented
 138  * as an request_sock.
 139  */
 140 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
 141                             struct request_sock *req)
 142 {
 143         struct sock *child = NULL;
 144         struct dccp_request_sock *dreq = dccp_rsk(req);
 145         bool own_req;
 146
 147         /* TCP/DCCP listeners became lockless.
 148          * DCCP stores complex state in its request_sock, so we need
 149          * a protection for them, now this code runs without being protected
 150          * by the parent (listener) lock.
 151          */
 152         spin_lock_bh(&dreq->dreq_lock);
 153
 154         /* Check for retransmitted REQUEST */
 155         if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
 156
 157                 if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_gsr)) {
 158                         dccp_pr_debug("Retransmitted REQUEST\n");
 159                         dreq->dreq_gsr = DCCP_SKB_CB(skb)->dccpd_seq;
 160                         /*
 161                          * Send another RESPONSE packet
 162                          * To protect against Request floods, increment retrans
 163                          * counter (backoff, monitored by dccp_response_timer).
 164                          */
 165                         inet_rtx_syn_ack(sk, req);
 166                 }
 167                 /* Network Duplicate, discard packet */
 168                 goto out;
 169         }
 170
 171         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
 172
 173         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
 174             dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
 175                 goto drop;
 176
 177         /* Invalid ACK */
 178         if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
 179                                 dreq->dreq_iss, dreq->dreq_gss)) {
 180                 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
 181                               "dreq_iss=%llu, dreq_gss=%llu\n",
 182                               (unsigned long long)
 183                               DCCP_SKB_CB(skb)->dccpd_ack_seq,
 184                               (unsigned long long) dreq->dreq_iss,
 185                               (unsigned long long) dreq->dreq_gss);
 186                 goto drop;
 187         }
 188
 189         if (dccp_parse_options(sk, dreq, skb))
 190                  goto drop;
 191
 192         child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL,
 193                                                          req, &own_req);
 194         if (child) {
 195                 child = inet_csk_complete_hashdance(sk, child, req, own_req);
 196                 goto out;
 197         }
 198
 199         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 200 drop:
 201         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
 202                 req->rsk_ops->send_reset(sk, skb);
 203
 204         inet_csk_reqsk_queue_drop(sk, req);
 205 out:
 206         spin_unlock_bh(&dreq->dreq_lock);
 207         return child;
 208 }
 209
 210 EXPORT_SYMBOL_GPL(dccp_check_req);
 211
 212 /*
 213  *  Queue segment on the new socket if the new socket is active,
 214  *  otherwise we just shortcircuit this and continue with
 215  *  the new socket.
 216  */
 217 int dccp_child_process(struct sock *parent, struct sock *child,
 218                        struct sk_buff *skb)
 219         __releases(child)
 220 {
 221         int ret = 0;
 222         const int state = child->sk_state;
 223
 224         if (!sock_owned_by_user(child)) {
 225                 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
 226                                              skb->len);
 227
 228                 /* Wakeup parent, send SIGIO */
 229                 if (state == DCCP_RESPOND && child->sk_state != state)
 230                         parent->sk_data_ready(parent);
 231         } else {
 232                 /* Alas, it is possible again, because we do lookup
 233                  * in main socket hash table and lock on listening
 234                  * socket does not protect us more.
 235                  */
 236                 __sk_add_backlog(child, skb);
 237         }
 238
 239         bh_unlock_sock(child);
 240         sock_put(child);
 241         return ret;
 242 }
 243
 244 EXPORT_SYMBOL_GPL(dccp_child_process);
 245
 246 void dccp_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
 247                          struct request_sock *rsk)
 248 {
 249         DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
 250 }
 251
 252 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);
 253
 254 int dccp_reqsk_init(struct request_sock *req,
 255                     struct dccp_sock const *dp, struct sk_buff const *skb)
 256 {
 257         struct dccp_request_sock *dreq = dccp_rsk(req);
 258
 259         spin_lock_init(&dreq->dreq_lock);
 260         inet_rsk(req)->ir_rmt_port = dccp_hdr(skb)->dccph_sport;
 261         inet_rsk(req)->ir_num      = ntohs(dccp_hdr(skb)->dccph_dport);
 262         inet_rsk(req)->acked       = 0;
 263         dreq->dreq_timestamp_echo  = 0;
 264
 265         /* inherit feature negotiation options from listening socket */
 266         return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg);
 267 }
 268
 269 EXPORT_SYMBOL_GPL(dccp_reqsk_init);